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11/22/16
What is a Plant?
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Multicellular
Eukaryotic
Autotrophic (photosynthesis)
Has cell walls containing
cellulose
Lack mobility (sessile)
Display “Alternation of
Generations” in their life cycle
Introduction to Plants
Plant Life Cycle
Plant Life Cycle – Alternation of Generations
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The lives of plants consist of
two alternating stages, or
generations: a gametophyte
generation and a
sporophyte generation.
One generation is dominant
over the other. This means
that it is larger and lasts
longer.
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The stage that produces
gametes (sperm and eggs) is
the gametophyte generation.
It is haploid.
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The stage that produces
spores is the sporophyte
generation. It is diploid.
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In most plants, the diploid
sporophyte generation is
dominant. In mosses, the
gametophyte dominates.
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What did they evolve from?
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Green Algae
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Similarities
Original Habitat
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prevents cells from drying out
! gives structural support
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contain chlorophyll
! have cell walls
made of cellulose
! store energy as
starch
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provides nutrients
! helps with reproduction
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(spore dispersal and meeting of sex cells)
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Adaptations for Land
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The simplest plants live surrounded by water
because water satisfies many of their needs:
Structures for retaining moisture
"Cuticle = waxy coating on the
outer surface of a plant
With time, plants adapted to live on land
Adaptations for Land
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Transport System
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Vascular tissue to move
nutrients and water
throughout the plant
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Also provides structure and
support for the plant
" Stomata = openings in the outer
layer of leaves & some stems
which regulate water loss and
allow gas exchange for
photosynthesis
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Adaptations for Land
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Reproductive Strategies
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adaptations that allow gametes to meet without water
No phyla, rather plants are organized into 12 divisions.
How are Plants Classified?
Non-Vascular Plants
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Are known as Bryophytes
Include mosses, liverworts,
& hornworts
1. No transport system
- no vascular “tubes” to transport
water & nutrients so must live in
moist habitats
2. Small size
- no support from vascular tissues
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Non-Vascular Plants
3. Do not have true roots,
stems and leaves
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Have root-like rhizoids which anchor
the plant and absorb nutrients
Absorb water through cell walls of
leaf-like structures; water moves via
osmosis.
Non-Vascular Plants - Reproduction
# Mosses display Alternation of Generations with the
Gametophyte stage being dominant & the sporophyte
stage being dependent on it
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4. Depend on water for
reproduction
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water is needed for the sperm to
swim to the egg
Vascular Plants
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Are known as Tracheophytes
Are true terrestrial plants
Spores produced by a
capsule (sporophyte)
A spore grows into a
leafy moss gametophyte
plant
The gametophyte
produces sperm which
must swim to fertilize the
egg
Vascular Plants
2. Larger size
- vascular tissues provide support
against gravity
1. Contain vascular tissue
- xylem transports water
- phloem transports food and
nutrients
3. Cuticle
- reduces water evaporation from
leaves and some stems
- run continuously through out
the plant body
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Seedless Plants
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Belong to the Class Filicineae
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Includes Ferns, horsetails, and club
mosses
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Have vascular tissue, but have a
rhizome underground instead of a
stem and leafy fronds
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Are the most primitive Tracheophytes
because they are still dependent on
water for reproduction
Today’s Agenda
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Did you know?
Notes
Practice
Seedless Plants - Reproduction
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Ferns display Alternation of Generations with the
Sporophyte stage being dominant
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Spores are produced in sori on
the underside of fronds
(sporophyte)
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A spore grows into a heartshaped gametophyte (prothallus)
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The prothallus produces gametes
that fuse to form a zygote which
grows into a frond.
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Water is necessary for
fertilization.
A sporophyte has the following
characteristics:
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Spore
Egg and sperm
Haploid
Diploid
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Seed Plants
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Gymnosperms
Include Gymnosperms and Angiosperms
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1. Have an improved vascular
system with true roots, stems
& leaves
2. Do not depend on water
for reproduction
3. Produce seeds
- a seed is a plant embryo
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1. Thin, needle-like leaves
= retains moisture
2. No water needed for reproduction
= allows diversity of habitats
Gymnosperms – Reproduction
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Gymnosperms display Alternation of Generations with the
Sporophyte stage being dominant
Which stage is dominate in
gymnosperms?
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The sporophyte (tree) produces
male and female cones.
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After pollination and fertilization,
the zygote will develop into a
naked seed attached a scale of
a female cone.
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Most cones you find on the
ground have lost their seeds.
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Gymnosperms have "naked" seeds
usually protected by cones.
They include evergreens, junipers,
cedars
Adaptations of Gymnosperms
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Sporophyte
Gametophyte
Both of the above
None of the above
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Which stage does the zygote belong
to?
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Gametophyte
Sporophyte
Gymnosperm
Angiosperm
Angiosperms
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Angiosperms are flowering
plants whose seeds are
produced and protected
within fruit.
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Further divided into
monocots and dicots.
Angiosperms -- Reproduction
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A flower is the reproductive structure of a plant
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Angiosperms -- Reproduction
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Fruits are essentially
Pollen is produced by the stamen.
Pollen moves away from the plant via pollinators (wind, birds, bees)
The pollen lands on the pistil of another plant and fertilizes the eggs
within the ovary
The flower petals fall off, the ovary develops into a fruit that encloses
the seeds
Each seed is composed of the plant embryo and a food source called
the endosperm
Fruits are dispersed in a variety of ways (wind, water, animals,
mechanical)
Fruits are not always edible, anything with a seed inside can be
considered a fruit (helicopters, acorns, dandelions)
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Plant ovaries
Seed bearing structures
Roots
Stems
Congratulations! You have been eating plant
ovaries!
http://www.youtube.com/watch?v=X7zW5W6XGeg
Angiosperms -- Reproduction
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Angiosperms display Alternation of Generations with the
Sporophyte stage being dominant
Angiosperms -- Reproduction
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Many plants can clone themselves, a process called
vegetative propagation
= use organs of the sporophyte stage (roots,
stems, leaves) to produce a new plant
- result in plants that are genetically identical
to the parent plant = clones
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Angiosperms -- Reproduction
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An orange tree branch is cut and then
attached to another tree. This would be
an example of _____________.
1. vegetative propagation
2. grafting
3. layering
4. cutting
https://uoitbio2013.w
ordpress.com/plantreproduction/sexualreproduction/
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